Osteochondritis dissecans of the knee predominantly affects adolescent and young adult patients. Many of these patients are involved in athletics, and this condition can have a dramatic impact on them. OCD can lead to pain, swelling, mechanical symptoms, and inability to continue to play sports. The affected knee may progress to degenerative arthritis while the patient is still young.

The etiology of OCD remains unknown, although several possibilities—including family history, repetitive micro-trauma, growth disorders, and ischemia—have been proposed. The incidence of this condition is unknown, although one study suggested an incidence of 29 cases per 100,000 males and 18 cases per 100,000 females. OCD can involve other joints including the shoulder, elbow, hip, and ankle, but the knee is the most common joint affected (Fig. 1).

The primary goals of treatment are to relieve pain, improve knee function, and prevent progression of the degenerative joint process. Surgical treatments are associated with some known risks, including infection, bleeding, venous thromboembolic events and persistent pain, although arthroscopic approaches have a relatively lower risk compared to more invasive approaches.

Although some surgical treatments can be performed arthroscopically, others may require an arthroscopic evaluation followed by more invasive treatments to salvage and/or reconstruct the cartilage and/or bone. Nonsurgical treatment also presents challenges because it is difficult to predict which stable juvenile OCD lesions will heal.

For these reasons, the AAOS undertook to develop clinical practice guidelines on the diagnosis and treatment of osteochondritis dissecans of the knee. At their meeting on December 4, 2010, the AAOS Board of Directors approved the new guideline, which includes 16 recommendations (Table 1).

The strength of each recommendation is based on the available evidence. Unfortunately, the evidence was insufficient or conflicting in most areas, so the work group was unable to make a recommendation for or against the intervention. Two of the recommendations received a weak recommendation, however, and four recommendations received a consensus recommendation.

The importance of evidence
The quality of the evidence is critical in the development of all clinical practice guidelines. The higher the quality of evidence, the more confidence one has in the recommendation. The work group considered only the best available evidence in the development of this guideline and recommendations, following a standard protocol used by the AAOS to identify the best evidence.

High-quality evidence was not available to support many of the treatments currently being used for patients with OCD of the knee. The strength of the recommendations reflects the degree of confidence in the recommendation. Strong or moderate-strength recommendations are based on Level III or higher studies that include comparative, controlled, and/or randomized prospective trials.

Many of the publications dealing with OCD of the knee are level IV evidence (case series). Case series studies do not provide causally valid relationships. They are descriptive studies and do not test the hypothesis of treatment efficacy; therefore, such studies are not appropriate to determine the efficacy of a treatment. Based on the weak available evidence from prospective case series and, in some cases, the overall lack of any available evidence, the work group was unable to support or oppose such common treatments as activity restrictions, immobilization, arthroscopic drilling, or cartilage salvage techniques for unstable lesions.

Both of the weak recommendations are related to imaging evaluation. For patients with knee symptoms, radiographs of the joint may be obtained to identify the lesion. For patients with radiographically apparent lesions, magnetic resonance imaging (MRI) may be used to further characterize the OCD lesion or identify other knee pathology.

Four of the recommendations were based on consensus. Consensus recommendations are made in the absence of reliable evidence, address a vitally important aspect of patient care that would be catastrophic to the patient if it were not addressed, and are based on the clinical opinion of the members of the work group, considering the known harms and benefits associated with the treatment.

The following are consensus recommendations:

• In the absence of reliable evidence, it is the opinion of the work group that symptomatic skeletally immature patients with salvageable unstable or displaced OCD lesions be offered the option of surgery.
• In the absence of reliable evidence, it is the opinion of the work group that symptomatic skeletally mature patients with salvageable unstable or displaced OCD lesions be offered the option of surgery.
• In the absence of reliable evidence, it is the opinion of the work group that patients who remain symptomatic after treatment for OCD have a history and physical examination, x-rays, and/or MRI to assess healing.
• In the absence of reliable evidence, it is the opinion of the work group that patients who have received surgical treatment of OCD be offered postoperative physical therapy.

The 10 inconclusive recommendations reviewed the surgical and nonsurgical recommendations for treatment.

Future research
The natural history of OCD of the knee remains unclear, and distinguishing between those lesions that may go on to heal and those that will not heal remains a challenge. High quality diagnostic, prognostic, and therapeutic studies that reported data separately for adults and children are rare. In fact, only 16 studies of OCD were of sufficient quality to be included in this clinical practice guideline.

The clinical guideline process provides an outline for future research areas. The following specific trials would meaningfully assist physicians in determining the diagnosis and treatment for patients with OCD of the knee. They would also support the development of future guidelines on the diagnosis and treatment of OCD.

• Inter- and intraobserver reliability studies on lesion classification for radiographs, MRI, and arthroscopy are needed.
• Prospective cohort studies of knee OCD lesions treated nonsurgically should be conducted to identify the independent predictors of success of nonsurgical management of an OCD lesion.
• Randomized controlled trials should be conducted to establish the optimal physical therapy and nonsurgical treatment strategies and physical therapy interventions for patients with OCD of the knee.
• Randomized controlled trials should be conducted to establish the optimal surgical treatment strategies for OCD of the knee.
• Randomized controlled trials should be conducted to determine the optimal postoperative management of patients with OCD of the knee.

Because OCD is a rare condition, many of these trials will need to be designed and conducted as multicenter studies, which allow for faster enrollment of an adequate sample size and may improve external validity.

We hope this guideline will be a roadmap for quality studies in these areas.

How the guidelines came to be (PDF)

Disclosure information: Dr. Shea—AAOS; American Orthopaedic Society for Sports Medicine; Pediatric Orthopaedic Society of North America (POSNA); Dr. Chambers—American Academy for Cerebral Palsy and Developmental Medicine; POSNA; Gait and Posture; Dr. Carey—no conflicts.

Kevin G. Shea, MD
Dr. Shea practices at Intermountain Orthopaedics in Boise, Idaho. He also is an adjunct associate clinical professor in the department of orthopaedics at the University of Utah School of Medicine in Salt Lake City, and served as the vice-chair of the work group that developed the Clinical Practice Guidelines on the Diagnosis and Treatment of Osteochondritis Dissecans of the Knee.